It's 1825, and Henry Rockcliff has been living in self-imposed exile in France for nearly a decade. But when his former army commander asks him to investigate a series of mysterious shipwrecks in his native England, and introduce a revolutionary lighthouse lens to his countrymen, he can't refuse. He couldn't save his sailor brother from a watery grave on that same stretch of coastline, but perhaps he can redeem himself by saving others.

Emelia Seaton has lived a quiet life in the seaside hamlet of Collington, England. She's anything but a conventional young lady; studying physics and mathematics for fun, befriending both fishermen and nobility, and spending hours practicing her archery skills in every condition. But in this quiet village, no one seems to mind her neurodivergent quirks.

Her carefully-constructed world is thrown into chaos, however, when two handsome men arrive in town. Edwin, her childhood best friend, has come home, and is making her blush in ways he never did when they were children. And Henry, the mysterious stranger, wants to install a Fresnel lens in the town lighthouse. It's unlike anything her physics-loving heart has ever seen; and Henry, with his uncanny sixth sense and unruffled demeanor, is unlike anyone she's ever known. Emelia will finally find the adventure she's been craving, along with more danger than she ever thought possible.